Co-founder CTO (Tech) H/F
Tech Co-founder CTO H/F
At OSS Ventures we're looking for a Co-founder CTO (Tech) to join one of our future ventures.
Meet your team
TL;DR
Position also known as: Co-founder CTO (Tech)
Location: Paris (regular on-site presence required for the first 9 months)
Salary range: Unpaid; founders share 75% equity, OSS retains 25%
Type of Contract: Founder equity agreement
Start date: As soon as possible
Companies Introduction
Our Ambition
We are reinventing the manufacturing world with software. OSS Ventures partners with bold entrepreneurs to build B2B SaaS companies that solve the hardest problems in industry.
Our Mission
To identify real industrial pain points and transform them into fast-scaling companies. From MVP to €500k ARR in under a year.
Our Story
Since 2019, we’ve launched 22+ ventures. Some failed, many thrived. Each cycle sharpened our playbooks and made our founders stronger.
Our Values
Trusting team excellence
Fail, learn, succeed
We eat what we kill
Compound the system
Build something the world needs
Think and do it quick
Our Team
You won’t be alone: you’ll co-found with a CEO, and work daily with OSS experts in product, tech, growth, HR, design, and fundraising. You’ll also get mentorship from seasoned CTOs who’ve been in your shoes.
Why we need you
What you will do
Lead all things tech & product. From MVP to scalable architecture, you’ll build a robust foundation while shaping the company with your co-founder.
In a nutshell
Own the product & technology.
Recruit, onboard, and lead your engineering team.
Support fundraising with technical due diligence & product narrative.
Ensure long-term scalability and robustness.
Broadly speaking
You’ll set the technical direction, ensure product-market fit, and co-lead the company’s vision, culture, and execution.
On a day-to-day basis
Code, prototype, talk to users, refine features, make architecture decisions, mentor engineers, and work closely with your co-founder CEO to push traction forward.
Who you’ll be working with
Your CEO co-founder, driving sales, strategy, and fundraising.
OSS core team: product, tech, growth, HR, design, VC experts.
Early customers from our industrial network.
CTO mentors who’ve scaled SaaS products before you.
Your profile to make this a success
Mandatory required skills
Hands-on product building: 5–7 years developing products end-to-end.
Team leadership: Experience recruiting, managing, and mentoring engineers.
B2B SaaS track record: Proven experience shipping scalable SaaS products.
Technical breadth: Strong in backend, infra & DevOps (bonus: AI/ML).
Systems thinking: Ability to design for scale and long-term robustness.
Communication: Strong collaborator, fluent in English (French is a plus).
This will be important in your job, we’ll teach what you currently miss
Industrial sector knowledge.
SaaS growth & go-to-market playbooks.
OSS fundraising tactics & investor storytelling.
We kindly advise you to think twice before applying if…
You’re not location-flexible for Paris during the first 9 months.
You’re not entrepreneurial by nature.
You’re not looking for a positively challenging role.
You’re uncomfortable working in both French and English.
Overall Expected Behaviors
You build, not theorize.
You move fast and learn faster.
You value feedback and collaboration.
You think systems, but ship MVPs.
What success looks like
Strong first engineering hires onboarded.
Product and architecture ready for rapid growth.
Tech narrative supporting a successful seed round.
Working conditions
Paris-based (75003)
Full-time, on-site for the first 9 months.
Intense but balanced: hands-on building with OSS support.
Process interview
Deep Tech Discussion – OSS CTO (1h).
Product & Market Fit Exploration – OSS Head of Product (1h).
Leadership & Soft Skills – OSS People Partner (1h).
Final Business Case – OSS Partners (2h).
FAQ
Q: Where do the startup ideas come from?
A: At OSS, the ideas come from us. We develop theses, identify market opportunities, and design concepts we believe the world needs. Founders join us to bring these ideas to life and build companies from scratch.
Q: Am I a founder or a hire at OSS?
A: You’re a founder, not an employee. That’s the big difference.
At OSS, we don’t hire CEOs or CTOs. We build companies with them. You’ll co-own the strategy, mission, and vision of the company with your co-founder.
Q: What type of co-founders are you recruiting?
A: We typically look for two core roles:
CEO (Sales) – someone who can own go-to-market, sales, fundraising, and build the commercial engine.
CTO (Tech & Product) – someone who can lead product vision, architecture, and technology execution.
Together, they complement each other and drive the startup’s growth.
Q: How do you make sure the match really works?
A: We don’t just rely on interviews. We test collaboration in real conditions:
Deep conversations on vision, values, and ways of working.
Co-creation sessions on a real business challenge to see how you think and decide together.
Trial phase (a few weeks) where you work as a founding team with OSS support before formalizing equity.
Q: How does equity work at OSS?
A: Founders split 75% equity (usually 50/50 between CEO & CTO), and OSS retains 25%.
We believe in true partnership, which means an equal split between co-founders. No “founding engineer” equity packages that dilute away — you’re a co-owner from day one
Q: Do I get a salary while building?
A: No. At OSS, you don’t get paid during the first months in the studio.
Instead, you focus entirely on building traction and raising your first seed round (with our support) to fund yourself and your team. Think of it as maximum alignment: if you succeed, you create a company with strong early revenues and fundraising momentum.
Q: What support do I get from OSS?
A: You’re not alone. You get:
A core team in product, growth, HR, design, and fundraising.
Playbooks refined across 20+ ventures (revenue, product-market fit, hiring, etc.).
Access to mentors (experienced CEOs & CTOs) who’ve done it before.
A network of industrial clients ready to test and adopt your product.
Hands-on help with fundraising, recruitment, and go-to-market experiments.
Q: What about customers? Do I have to find them myself?
A: We help you get users fast.
Instead of over-building in a vacuum, you’ll ship an MVP in the first months and test it directly with our network of design partners and early adopters. Our GTM experts run weekly experiments to accelerate acquisition and feedback.
Q: How is my startup de-risked?
A: OSS has launched 20+ ventures, and we’ve seen patterns repeat.
We validate ideas with market research before building. We provide benchmarks, fundraising decks, hiring pipelines, and frameworks for early decisions. That means you avoid costly mistakes and learn from proven approaches.